One such interrupter unit is known, by way of example, from Laid-Open Specification DE 32 11 272 A1. In the known arrangement, a part of the interrupter unit is held by a deflection shroud which acts as a mounting element. The deflection shroud surrounds a rated current contact piece, which is in the form of a hollow channel. A quenching gas, which is produced in the switching gap during a switching process, continues to flow through the hollow channel from the switching gap. The quenching gas is deflected on the deflection shroud, and is passed out of the interrupter unit outside the hollow channel, in the opposite direction of the flow direction of the quenching gas in the interior of the rated current contact piece. A design as this has only a relatively short outlet flow path for the quenching gas. Furthermore, the quenching gas, which is enriched with decomposition products, is passed out in the immediate vicinity of the switching gap. The webs which run from the outlet flow shroud to the rated current contact piece and to which the rated current contact piece is fitted are located directly in the outlet flow path of the quenching gas, and increase the flow resistance of this path. With the quenching gas being routed in this way, cooling and rapid onward movement of the quenching gas from the switching gap are possible only to a restricted extent.
Furthermore, FIG. 9 in U.S. Pat. No. 4,236,053 discloses an interrupter unit in which the quenching gas flowing away from the switching gap is first of all moved away from the switching gap and a labyrinth-like channel is formed by an arrangement of different outlet flow shrouds, in which the quenching gas flow direction is deflected twice through about 180°. This results in a relatively long outlet flow path for the quenching gas within a compact area. The outlet flow path there is in this case substantially formed by attaching deflection shrouds to the contact pieces, which partially support the interrupter unit. Since the contact pieces are physically designed as mechanically load-bearing elements which are surrounded by the outlet flow shrouds, this admittedly results in optimized arrangements within the interior of the outlet flow shrouds with regard to the mechanical configuration, but the outlet flow path has a high flow resistance.